A. Field of the Invention
This invention relates primarily to faucets which control the mixing of hot and cold water. More particularly, the invention relates to faucets of the foregoing type wherein a movable disk is both rotated and directed in a linear manner over a stationary disk by an operating spindle.
B. Description of the Art
There are problems with certain mixing valves which utilize movable and stationary disks (e.g. ceramic disks). Ceramic material in movable disks is very hard and thus causes an abrasion problem when engaged over an extended period of time by a metallic or plastic driving spindle. Such a problem can be particularly of concern when a valve is employed like that described in U.S. Pat. No. 3,965,936 when a movable ceramic plate is directly engaged by a metallic or plastic spindle 37, and the spindle seeks to cause both rotation and translation of the disk.
Another problem with faucets of this type is the amount of force on the spindle needed to achieve proper rotation and translation of the valve disk. This is of greatest concern with small units.
Many of the prior art units are of the 35 or 42 mm. size. As the size of the spindle lower end is reduced so that it will fit through a smaller top bonnet, it becomes more and more difficult to achieve valve control using an integral lower end of the spindle.
Another factor is that to reduce costs, it is desirable to maximize use of plastic in the components above the disks yet to utilize a minimum amount of plastic and still maintain rigidity and stability. Still another cost factor is in having to machine metallic spindles to fit a ceramic disk or a drive member.
Thus, it can be seen that a need exists for an improved mixing valve.